1. Field of the Invention
My invention relates to methods and apparatus for assisting motor vehicle operators in safely operating their vehicles, and more particularly to methods and apparatus for enabling motor vehicle operators to back their vehicles into pre-determined close proximity to buildings, walls, or other obstacles, without striking the same. My invention further particularly relates to methods and apparatus for enabling the operators of dump trucks and the like to back their vehicles into pre-determined close proximity to open trenches and the like, whereby to deliver their loads into said open trenches or the like with precision, and without breaking down the walls of said open trenches or the like.
2. Description of the Prior Art
It is known in the prior art to provide periscopes or open optical systems operating on the periscope principle to assist the operators of motor vehicles in backing their vehicles into close proximity to obstacles and other hazards.
For example, a prior art patent shows a delivery truck of the type used in making parcel deliveries in large cities, equipped with a periscope tube or housing which is affixed to and extends along substantially the entire length of the roof of the truck, and overhangs the rear edge of the roof of the truck. This periscope tube contains a forward mirror which coacts (through a hole in the roof of the truck) with a viewing mirror affixed to the dashboard of the truck, and also coacts with a mirror in the overhanging rearward portion of the tube, whereby the operator of the delivery truck can view the area immediately behind his truck as seen from directly overhead. As appears from the drawings of this patent, the mirrors of the periscope are quite large, apparently in order to provide a sufficiently broad field of view of the area behind the truck for the driver, and thus the top of the periscope tube is a considerable distance above the top of the truck, reducing the ability of the truck to clear the tops of tunnels and other passages, doorframes, etc. Additionally, it can be seen that the cost of installing the periscope, including the cutting of a substantial hole in the roof of the truck, is sufficiently great to prevent the widespread adoption of this prior art periscope system.
The prior art also teaches the employment of an auxiliary outside rear-view mirror mounted outboard of the left wall of the vehicle, and also outboard of the rear wall of the vehicle, and so vertically positioned that this auxiliary mirror can coact with the existing rear-view mirror to provide a periscope whereby the vehicle operator can view the area behind the vehicle while seated in the driving position.
Such prior art auxiliary outside mirrors, however, are subject to being put out of alignment or broken by impact with stationary objects or other vehicles due to the exposed location in which they are necessarily mounted, and, as will be obvious to those having ordinary skill in the art, even slight mirror mis-alignments can render these prior art systems completely inoperative.
Further, the image of the area behind the vehicle provided by these prior art systems can be obscured to the point of practical uselessness by vibration of the auxiliary mirror due to engine vibration, or the like.
Yet further, the effective aperture or viewing area of these prior art systems is seriously restricted due to the fact that the auxiliary mirror is practically limited in size by the location in which it must be mounted, which location dictates that the mirror must be small in order to minimize the possibility of its striking other vehicles or stationary objects.